Federal Government support for mental retardation research is increasing, and there is a critical need to attract talented new investigators to the filed, so that this increase in research support can have maximum impact. Moreover, these new investigators must be prepared to excel in a research field that is inherently interdisciplinary. Few new PhDs have had the experience necessary to compete in this climate. Our goal is to attract new investigators to the field of mental retardation, and provide these investigators with career-building interdisciplinary and collaborative experiences. The training program is designed to nurture the development of researchers who will meet national research priorities in the field of mental retardation and developmental disabilities. This 5-year training grant will provide training and support to a total of 16 postdoctoral traineeships, each lasting two years.